GONG p-mode frequency changes with solar activity

We present a correlation analysis of GONG p-mode frequencies with nine solar activity indices for the period 1995 August to 1997 August. This study includes spherical harmonic degree in the range 2 to 150 and the frequency range of 1500-3500 \mu Hz. Using three statistical tests, the measured mean frequency shifts show strong to good correlation with activity indices. A decrease of 0.06 \mu Hz in frequency, during the descending phase of solar cycle 22 and an increase of 0.04 \mu Hz in the ascending phase of solar cycle 23 is observed. These results provide the first evidence for change in p-mode frequencies around the declining phase of solar cycle 22 and beginning of new cycle 23. This analysis further confirms that the temporal behaviour of the solar frequency shifts closely follow the phase of the solar activity cycle.Comment: 14 pages, 3 figures. To appear in Ap.

Altruism and social integration

We develop a two-stage experimental protocol by which i) we elicit the social network within a group of undergraduate students and ii) we measure their altruistic attitudes by way of a standard Dictator game. We observe that more socially integrated subjects are also more altruistic, as betweenness centrality and reciprocal degree are positively correlated with the level of giving, even after controlling for the effect of social distance, which has been shown to affect giving. Our findings suggest that social distance and network position are complementary determinants of altruistic behavior

Linear second-order differential equations for barotropic FRW cosmologies

"Simple linear second-order differential equations have been written down for FRW cosmologies with barotropic fluids by Faraoni. His results have been extended by Rosu, who employed techniques belonging to nonrelativistic supersymmetry to obtain time-dependent adiabatic indices. Further extensions are presented here using the known connection between the linear second-order differential equations and Dirac-like equations in the same supersymmetric context. These extensions are equivalent to adding an imaginary part to the adiabatic index which is proportional to the mass parameter of the Dirac spinor. The natural physical interpretation of the imaginary part is related to the particular dissipation and instabilities of the barotropic FRW hydrodynamics that are introduced by means of this supersymmetric scheme.

Solar cycle variations of large frequency separations of acoustic modes: Implications for asteroseismology

We have studied solar cycle changes in the large frequency separations that can be observed in Birmingham Solar Oscillations Network (BiSON) data. The large frequency separation is often one of the first outputs from asteroseismic studies because it can help constrain stellar properties like mass and radius. We have used three methods for estimating the large separations: use of individual p-mode frequencies, computation of the autocorrelation of frequency-power spectra, and computation of the power spectrum of the power spectrum. The values of the large separations obtained by the different methods are offset from each other and have differing sensitivities to the realization noise. A simple model was used to predict solar cycle variations in the large separations, indicating that the variations are due to the well-known solar cycle changes to mode frequency. However, this model is only valid over a restricted frequency range. We discuss the implications of these results for asteroseismology.Comment: 9 pages, 11 figures, accepted for publication in MNRAS, references updated, corrections following proof

Influencia de grelina y leptina sobre alteraciones psiquiátricas en sujetos con obesidad

La obesidad (índice de masa corporal [IMC] > 30 kg/m2) se define como el exceso en la proporción del tejido adiposo; consecuencia de un ingreso calórico superior al gasto energético del individuo. Es considerada un problema inflamatorio, sistémico, crónico y recurrente que causa diversas complicaciones. Esta enfermedad se ha relacionado con diversos problemas metabólicos y fisiológicos ampliamente estudiados; además de psicopatológicos.La obesidad es un problema de salud pública en diversos países, principalmente en Norteamérica. Se ha observado que sujetos que presentan obesidad manifiestan numerosas alteraciones psiquiátricas, entre ellas: depresión, ansiedad y trastorno por atracón. Por ello, diversos estudios han llegado a la conclusión de que las hormonas gastrointestinales fungen un papel crucial en el establecimiento de conductas, siendo la orexigénica grelina y la anorexigénica leptina 2 de las hormonas con mayor participación activa. Dicha intervención se debe a que ambas hormonas presentan receptores en sistema nervioso central, primordialmente en áreas del sistema límbico, regulador crucial de conductas hedónicas. Por lo tanto, en la presente revisión bibliográfica describiremos el papel de la grelina y la leptina sobre la expresión de conductas psicopatológicas comunes en sujetos que padecen obesidad

Beetles (Coleoptera) of Peru: A Survey of the Families. Scarabaeoidea

The 1042 species of Scarabaeoidea known to occur in Peru are listed with their taxonomic placement in families, subfamilies, and tribes